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Guard log_merge, srch_root, and mounted_client item printers

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Scoutfs print segfaults walking a log_merge btree that has more than one
level. print_btree_block() prints parent (level > 0) items via
print_block_ref(), which invokes the item callback with a NULL value to
print the key portion before printing the child ref:

	func(key, 0, 0, NULL, 0, arg);

print_log_merge_item immediately casts val and reads a field,
dereferencing NULL. A log_merge of a single leaf block (height 1) never
hits the parent path; one with height > 1 crashes on the first parent
item:

  scoutfs[22043]: segfault at 8 ip 0000000000408ef0 sp 00007fffc5edd8b0 error 4

  #0  0x0000000000408ef0 in print_log_merge_item ()
  #1  0x000000000040958d in print_btree_block.constprop.0.isra ()
  #2  0x000000000040a471 in print_cmd ()
  #3  0x0000000000404264 in cmd_execute ()
  #4  0x00000000004025c9 in main ()

print_mounted_client_entry has the same bug: it casts val and reads
mcv->addr / mcv->flags with no NULL guard, so a mounted_clients btree of
height > 1 segfaults the same way. print_srch_root_item guards NULL but
casts to scoutfs_srch_compact or scoutfs_srch_file without bounds
checking, so a short or malformed item reads past its end.

Fix all three: return early when val is NULL (printing just the key for
the parent ref where applicable), and bounds-check val_len before each
cast so a short item is reported instead of read past its end.

Signed-off-by: Auke Kok <auke.kok@versity.com>
This commit is contained in:
Auke Kok
2026-07-23 09:14:31 -07:00
parent 78127bf195
commit 70b80695cb
1 changed files with 49 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
utils/src/print.c
+49 -1
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@@ -375,6 +375,11 @@ static int print_srch_root_item(struct scoutfs_key *key, u64 seq, u8 flags, void
if (val) {
if (key->sk_type == SCOUTFS_SRCH_PENDING_TYPE ||
key->sk_type == SCOUTFS_SRCH_BUSY_TYPE) {
if (val_len < sizeof(*sc)) {
printf(" (short srch compact value: val_len %u)\n",
val_len);
return 0;
}
sc = val;
printf(" compact %s: nr %u flags 0x%x\n",
key->sk_type == SCOUTFS_SRCH_PENDING_TYPE ?
@@ -387,6 +392,11 @@ static int print_srch_root_item(struct scoutfs_key *key, u64 seq, u8 flags, void
SRF_A(&sc->in[i].sfl));
}
} else {
if (val_len < sizeof(*sfl)) {
printf(" (short srch file value: val_len %u)\n",
val_len);
return 0;
}
sfl = val;
printf(" "SRF_FMT"\n", SRF_A(sfl));
}
@@ -398,9 +408,25 @@ static int print_srch_root_item(struct scoutfs_key *key, u64 seq, u8 flags, void
static int print_mounted_client_entry(struct scoutfs_key *key, u64 seq, u8 flags, void *val,
unsigned val_len, void *arg)
{
struct scoutfs_mounted_client_btree_val *mcv = val;
struct scoutfs_mounted_client_btree_val *mcv;
struct in_addr in;
/*
* Parent block items reference child blocks and have no value;
* print_block_ref() calls us with a NULL val just to print the key.
*/
if (!val) {
printf(" rid %016llx\n", le64_to_cpu(key->skmc_rid));
return 0;
}
if (val_len < sizeof(*mcv)) {
printf(" rid %016llx (short mounted client value: val_len %u)\n",
le64_to_cpu(key->skmc_rid), val_len);
return 0;
}
mcv = val;
memset(&in, 0, sizeof(in));
in.s_addr = htonl(le32_to_cpu(mcv->addr.v4.addr));
@@ -419,8 +445,17 @@ static int print_log_merge_item(struct scoutfs_key *key, u64 seq, u8 flags, void
struct scoutfs_log_merge_complete *comp;
struct scoutfs_log_merge_freeing *fr;
/*
* Parent block items reference child blocks and have no value;
* print_block_ref() calls us with a NULL val just to print the key.
*/
if (!val)
return 0;
switch (key->sk_zone) {
case SCOUTFS_LOG_MERGE_STATUS_ZONE:
if (val_len < sizeof(*stat))
goto bad_len;
stat = val;
printf(" status: next_range_key "SK_FMT" nr_req %llu nr_comp %llu seq %llu\n",
SK_ARG(&stat->next_range_key),
@@ -429,12 +464,16 @@ static int print_log_merge_item(struct scoutfs_key *key, u64 seq, u8 flags, void
le64_to_cpu(stat->seq));
break;
case SCOUTFS_LOG_MERGE_RANGE_ZONE:
if (val_len < sizeof(*rng))
goto bad_len;
rng = val;
printf(" range: start "SK_FMT" end "SK_FMT"\n",
SK_ARG(&rng->start),
SK_ARG(&rng->end));
break;
case SCOUTFS_LOG_MERGE_REQUEST_ZONE:
if (val_len < sizeof(*req))
goto bad_len;
req = val;
printf(" request: logs_root "BTROOT_F" logs_root "BTROOT_F" start "SK_FMT
" end "SK_FMT" input_seq %llu rid %016llx seq %llu flags 0x%llx\n",
@@ -448,6 +487,8 @@ static int print_log_merge_item(struct scoutfs_key *key, u64 seq, u8 flags, void
le64_to_cpu(req->flags));
break;
case SCOUTFS_LOG_MERGE_COMPLETE_ZONE:
if (val_len < sizeof(*comp))
goto bad_len;
comp = val;
printf(" complete: root "BTROOT_F" start "SK_FMT" end "SK_FMT
" remain "SK_FMT" rid %016llx seq %llu flags %llx\n",
@@ -460,6 +501,8 @@ static int print_log_merge_item(struct scoutfs_key *key, u64 seq, u8 flags, void
le64_to_cpu(comp->flags));
break;
case SCOUTFS_LOG_MERGE_FREEING_ZONE:
if (val_len < sizeof(*fr))
goto bad_len;
fr = val;
printf(" freeing: root "BTROOT_F" key "SK_FMT" seq %llu\n",
BTROOT_A(&fr->root),
@@ -472,6 +515,11 @@ static int print_log_merge_item(struct scoutfs_key *key, u64 seq, u8 flags, void
}
return 0;
bad_len:
printf(" (short log merge value: zone %u val_len %u)\n",
key->sk_zone, val_len);
return 0;
}
static int print_alloc_item(struct scoutfs_key *key, u64 seq, u8 flags, void *val,